This invention pertains to a method of providing temperature control for series-connected reactors. It pertains particularly to a temperature control arrangement and method for a vapor feed stream into a fixed bed type second reactor located downstream from an ebullated bed catalytic first reactor.
Catalytic reactors are often operated in series flow arrangement, and sometimes it is particularly desirable to feed a vapor fraction from a first reactor such as an ebullated catalyst bed reactor into a second fixed bed catalytic reactor for further processing. It is also desirable to independently control the reaction temperatures in each reactor in an effective and thermally efficient manner. Such control of feed conditions into the second reactor has usually required additional process steps and often requires undesirable reductions in pressure for the feed to the second reactor. U.S. Pat. No. 3,322,665 to Chervenak et al discloses a two-stage hydroconversion process for a petroleum feed in which effluent from a first reactor is cooled against recycle hydrogen upstream of a second reactor. The present invention provides a convenient and practical method for controlling the vapor feed temperature and composition into a second reactor relatively independently of the first reactor outlet temperature, by using a series-connected heat exchanger arrangement with only minimal reduction in feedstream pressure to the second reactor.